436 THE CANADIAN NATURALIST. [Dec. 



with little openings along each side, though there certainly 

 appear to be only open farrows in the specimens examined. 



It is worthy of note, in this connection, that there certainly are 

 species, agreeing exactly in all other known characters with this 

 genus, that have no open furrow along the outer or ventral side 

 of the arms, which are distinctly seen to be round on the outer 

 side, and show there a double series of interlocking pieces along 

 their entire length, while the tentacula connect along the inner, 

 or under side, as the arms are seen hanging down. This is 

 clearly seen to be the case in a beautiful specimen of G. typus 

 (=^Trematftcrinus typus, Hall) in Mr. Wachsmuth's collection, 

 and we can scarcely doubt that in this species there is an open 

 farrow on the inner (under) or dorsal side of the arms. If not, 

 the arms must be tubular, in consequence of having the ambula- 

 cral canal enclosed all around, excepting at the points where the 

 the tentactila connect along each side. 



3. Cyatkoarinus. Miller. Specimens of this genus showing 

 the vault (more properly the ventral disc) have very rarely been 

 seen. In England a few examples have been found, and these 

 have been supposed to show two openings, one central and another 

 lateral : the latter, according to Prof. PhUlips' and Mr. Austin's 

 figures, being provided with a s-lender marginal tube, or so-ca'led 

 proboscis. Some of Mr, Wachsmuth's specimens, however, of 

 C. malvaceus and C. loicensis. Hall, showirg the vault, have 

 led us to doubt the existence of a central opening in the vault of 

 this genus, when the specimens have this part entire. The 

 specimen of C. malvaceus shows the remains of the usual narrow 

 lateral proboscis, and also has an opening in the middle of the 

 vault, but from the appearance of this opening, as well as from 

 the structure of the vault of a specimen of C loicensis, in 

 which this op>ening is closed, we can scarcely doubt that it was 

 also closed in the specimen of C. malvaceus, when entire. The 

 remaining parts of the vault of the C. malvaceus mentioned consist 

 of only five comparatively large pieces, alternating with the upper 

 inner edges of the first radial pieces, — the one on the anal side 

 being larger than the others, and forming the base of the inner 

 side of the proboscis. These five pieces connect with each other 

 laterally and extend inward some distance, but not so far as to 

 meet at the centre, where there is a sub-semicircular opening, 

 nearly as large as that in the remaining base of the proboscis. 

 Along each of the Butures between the five vault pieces mentioned, 



